A modified ERG technique and the results obtained in X-linked retinitis pigmentosa.

Arden, G B; Carter, R. M.; Hogg, Chris; Powell, D. J.; Ernst, Wolfgang; Clover, G. M.; Lyness, A L; Quinlan, M P

doi:10.1136/bjo.67.7.419

Cited by 123 publications

(58 citation statements)

References 19 publications

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“…With regard to the b-wave, a reduction in Vmax is generally thought to reflect a loss of photoreceptors [24,48,49], although it has been suggested that the local loss of rods may influence K more than Vmax [50]. The parameter K reflects the sensitivity of the retina, and will generally be increased either if the healthiest region of the retina has receptors less sensitive than normal, or if a large proportion of the photoreceptors have a decreased sensitivity [50].…”

Section: Discussionmentioning

confidence: 99%

“…An increase in PhNR amplitude with increasing stimulus intensity has been described, with saturation occurring at around 2.0 log phot td.s [10,11,14], however no attempt has been made to fit this intensity-response data with a mathematical model, thereby allowing a quantitative analysis of the parameters of the intensity-response relationship. The Naka-Rushton function (see Equation 1) is a sigmoidal curve which has been shown to describe the increase in b-wave amplitude, measured from the minimum point of the a-wave, with increasing stimulus intensity [24][25][26]. This reportedly provides a good fit to data across a range of intensities, although the relationship breaks down at high intensities for both light [27] and dark-adapted [28] b-waves.…”

Section: Introductionmentioning

confidence: 93%

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The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

2011

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

2011

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“…Furthermore, the secondary rod pathway may saturate at higher flash strengths. Few predictions have been made in the literature on the behaviour of rod pathway responses to flickers of high flash strengths [35,36]. However, in the subsequent accompanying study, we will describe the 15 Hz responses of an achromat.…”

Section: Discussionmentioning

confidence: 99%

An extended 15 Hz ERG protocol (1): the contributions of primary and secondary rod pathways and the cone pathway

et al. 2011

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The minimum in the amplitude versus flash strength curve of dark-adapted 15 Hz electroretinograms (ERGs) has been attributed to interactions between the primary and secondary rod pathways. The 15 Hz ERGs can be used to examine the two rod pathways in patients. However, previous studies suggested that the cone-driven pathway also contributes to the 15 Hz ERGs for flash strengths just above that of the minimum. We investigated cone pathway contributions to improve upon the interpretation of (abnormal) 15 Hz ERGs measured in patients. We recorded 15 Hz ERGs in five healthy volunteers, using a range of flash strengths that we extended to high values. The stimuli were varied in both colour (blue, green, amber, and red) and flash duration (short flash and square wave) in order to stimulate rods and cones in various ways. The differences in the responses to the four colours could be fully explained by the spectral sensitivity of rods for flash strengths up to approximately 12.5 log quantaÁdeg -2 . At higher flash strengths, higher-order harmonics appeared in the responses which could be attributed to cones being more sensitive than rods to higher frequencies. Furthermore, the amplitude curves of the blue and green responses showed a second minimum suggesting rod to cone interactions. We present a descriptive model of the contributions of the rod and cone pathways. In clinical application, we would advise using the short flash flicker instead of the square wave flicker, as the responses are of larger amplitude, and cone pathway contributions can be recognized from large higher-order harmonics.

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“…Most XLRP carriers can be identified on the basis of fundus findings and ERG changes; however, 10-30% of carriers show no abnormal ERG or fundus finding. 1,4,5,9 Although XLRP is the least common genetic type of RP, accounting for 6-17% of familial retinitis pigmentosa cases, it is extremely devastating. 1,12,13 In the first or second decade of life, affected individuals experience a decrease in peripheral and night vision, and the disease often leads to partial or complete blindness in the fourth or fifth decade of life.…”

Section: Introductionmentioning

confidence: 99%

Cellular imaging demonstrates genetic mosaicism in heterozygous carriers of an X-linked ciliopathy gene

Hong

et al. 2013

Eur J Hum Genet

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X-linked retinitis pigmentosa (XLRP) is the least common genetic type of retinitis pigmentosa; however, it has extremely devastating consequences to patients' activities of daily living. RPGR and RP2 genes expressed in the photoreceptor sensory cilia are predominantly implicated in XLRP; however, the interpretation of genetic mutations and their correlation with clinical phenotypes remain unknown, and the role of these genes in photoreceptor cilia function is not completely elucidated. Therefore, we evaluated structural characteristics in five female obligate carriers of XLRP by using state-of-the-art non-invasive imaging methods, including adaptive optics (AO) scanning laser ophthalmoscopy (SLO). In all five carriers examined, qualitative and quantitative analyses by AO SLO imaging revealed a mosaic pattern of cone disruption, even in the absence of visual symptoms, normal visual acuity and normal macular thickness, on optical coherence tomography and mildly subnormal full-field cone electroretinographic findings. As the technique is sensitive to the level of a single cone, the ability to visualize the cone cells in vivo should be especially useful in other retinal diseases. In addition, further investigation of XLRP carriers may yield insight into how cone structures change over time and ultimately enable understanding of the role of RPGR and RP2 in cone cell survival. European Journal of Human Genetics (2013Genetics ( ) 21, 1240Genetics ( -1248 doi:10.1038/ejhg.2013; published online 27 February 2013Keywords: X-linked retinitis pigmentosa carrier; photoreceptor layer; adaptive optics scanning laser ophthalmoscopy INTRODUCTIONIdentification of X-linked retinitis pigmentosa (XLRP) carriers is challenging and has serious implications for genetic counseling. Female XLRP carriers usually have normal, or close to normal, visual acuity, but often show some degree of fundus changes, including sectorial or peripheral pigmentary deposits and a tapetal-like reflex (TLR), 1 as well as abnormal fundus. Many previous studies have detailed the prevalence of abnormal fundus photography, 1,2 vitreous fluorophotometry, 3 infrared (IR) reflectance images, 1,2 electroretinographic (ERG), 4,5 psychophysical 6 and flicker-fusion 7 findings in such carriers. More recently, several studies have investigated XLRP carriers with advanced devices, including FAF, 8 multifocal ERG 9 and OCT 10,11 to reveal clinical phenotypes of XLRP. Most XLRP carriers can be identified on the basis of fundus findings and ERG changes; however, 10-30% of carriers show no abnormal ERG or fundus finding. 1,4,5,9 Although XLRP is the least common genetic type of RP, accounting for 6-17% of familial retinitis pigmentosa cases, it is extremely devastating. 1,12,13 In the first or second decade of life, affected individuals experience a decrease in peripheral and night vision, and the disease often leads to partial or complete blindness in the fourth or fifth decade of life. 14 In contrast to the severe retinal degeneration in affected men, female carriers of t...

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A modified ERG technique and the results obtained in X-linked retinitis pigmentosa.

Cited by 123 publications

References 19 publications

The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

An extended 15 Hz ERG protocol (1): the contributions of primary and secondary rod pathways and the cone pathway

Cellular imaging demonstrates genetic mosaicism in heterozygous carriers of an X-linked ciliopathy gene

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